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Saturday, May 2, 2015

Mars
has the twin attributes of being close by (at least by solar system standards)
and retaining a record of its earliest epoch (lost on Earth) when life might
have formed.These have made it a
popular destination with five orbiters currently operating around it and two
rovers driving across its sands.At
least as many new missions are in various stages of development or are proposal,
ranging from hardware headed for the launch pad in a few months to some that eventually
may prove to be no more than vaporware.

In the
last two months, there have been significant news about the European-Russian
2018 mission and about NASA’s 2020 rover.NASA also has announced that it would like to send a new orbiter to the
Red Planet in the early 2020’s.These
announcements will be the meat of this blog post, but first I’ll quickly run
through the status of other planned and proposed missions.

Six
craft to launch as four missions are firmly in development and have fully
funded budgets.Europe’s Trace Gas
Orbiter and its Schiaparelli technology demonstration lander are in assembly
and on track to launch next January.NASA’s InSight geophysical lander also is in assembly for its launch
next March, although the mission’s principal investigator reports that the
schedule is tight.Design of the 2018
ExoMars European rover and Russian lander are on track as is NASA’s 2020 rover

Icebreaker concept.Credit: McKay/NASA

It’s
likely that another mission to return to the Martian northern polar plains has
been proposed for the NASA Discovery program.The Phoenix lander explored these regions, but was frustrated by clumpy
soils that made it difficult to deliver samples to its instruments.What the Phoenix spacecraft did find was a
layer of ice just below the surface dust that could provide a habitat for
life.The proposed Icebreaker mission
would follow up on the Phoenix mission with a sampling system that would drill
well into the ice and is designed to work with the clumpy soil.The lander, which would be a near copy of the
Phoenix and InSight landers, would carry new instruments that would search for
signs of life.While this proposal has
received considerable publicity, I haven’t heard whether it was actually
proposed.Sometimes, proposers learn as
they develop their plans that their missions would not fit within the tight
budgets of Discovery missions.(I’ve
heard of one proposal that I was excited about that wasn’t submitted for the
current Discovery selection for this reason.)If the Icebreaker mission was proposed and is selected (beating out 27
other proposals), it would launch in 2021.

China
announced plans a few months ago for its own Martian rover mission to launch in
2020.More recently, a Chinese official
stated that the budget for this mission was unlikely to be approved in time for
a 2020 launch.

There
have also been press accounts that India is considering a second Mars mission
that might be an orbiter and/or a lander.I haven’t heard whether the budget for a follow on mission has been
approved or not.

And now
on to the major announcements of the last couple of months.

The
2018 ExoMars mission will use a Russian landing system and platform to deliver a
European rover to the surface.Russia
has planned to use the landing platform as a scientific station after the rover
rolls off it.Until recently, I’ve been
unable to find any details about the planned experiments.Now an announcement of opportunity has been
issued for European scientists to contribute to Russian-led instruments and to
propose their own additions (see here).

The
Russian landing stage and long term science station with the European rover on
top prior to its deployment.Credit:
Russian Academy of Science Space Research Institute.

The
documents state that the priorities for the stations are:

“Priority
1:

•
Context imaging;

•
Long-term climate monitoring and atmospheric investigations.

Priority
2:

•
Studies of subsurface water distribution at the landing site;

•
Atmosphere/surface exchange;

•
Monitoring of the radiation environment

•
Geophysical investigations of Mars’ internal structure.”

The
documents lists the names only for an ambitious suite of instruments, although
it’s not always clear what instruments are already firmly planned versus those
that might be added by European scientists.The instruments break down into several groups:

This
suite would be a highly capable science station.For example, the station will monitor both
the physical state of the atmosphere (temperature, pressure, dust load, etc.)
as well has changes in its composition (presumably with a focus on changes in
trace gases to provide ground truth measurements for the 2016 Trace Gas
Orbiter).The listed target weight for the
seismometer suggests a simpler instrument than the InSight lander will
carry.Having a second seismometer would
help geophysicists narrow down the source locations of Mars quakes.The sensitivity of this new seismometer may
be limited if there isn’t a way to lower it to the ground to isolate it from
the vibrations within the station.

What I
am surprised by is that the call for instruments includes requests for
significant pieces of hardware to be supplied by European scientists for
Russian-led instruments.In terms of
instrument and spacecraft development, 2018 is practically around the
corner.I will be interested to see how
the Russians and Europeans manage the selection, development, testing, and
integration of these instruments in this short time frame.Perhaps considerable work has already been
done or there are flight-ready designs already available.

Two
years after the ExoMars station and rover arrive, NASA will land its 2020
rover.The rover itself will be a near
copy of the Curiosity rover currently on Mars, but with a next generation
instrument suite.A major new goal will
be to select and cache a suite of samples that a later mission might collect
and return to Earth.

2020
NASA Mars rover concept drawing.Credit:
JPL/NASA

Each
sample will be about the size of a stubby pencil.Previously, NASA had planned to put each
sample into a canister as it was collected.This canister would then be placed on the surface for later collection
after it was full.NASA has announced a
major change in how these samples will be cached (see here).

The
original plan had two key limitations.First, as the canister acquired more and more samples, it would become
an increasingly precious resource.This
would lead the mission’s operators to become increasingly conservative in their
operation of the rover.Should they, for
example, explore an interesting looking ridge, but one where if the rover fails
the rock face would prevent a future mission from being able to reach the
canister?Second, there was no good way
to remove samples once they were in the canister.What if the canister was full and then scientists
find the one sample they absolutely want to collect for return to Earth?

In
the new plan, dubbed the Adaptable Cache, the rover would still drill out
samples and put them into sample tubes.Then instead of putting the tubes into a canister, the rover would place
them on the surface and then move on.A
future sample return mission would carry a rover that would pick up the samples
and place them into a canister it carries.This way the 2020 rover can cache more samples than could be returned
and scientists would send the subsequent rover to pick up only the most
important ones.Even with the old scheme
where the 2020 rover carried the canister, the follow on mission would still
need a rover to fetch the canister.Now
that follow on rover would need a more capable arm to pick up tubes lying on
the surface and place them into its own canister.

The
new rover will also have an upgrade to its engineering cameras.On Curiosity, the navcam/hazcam cameras used
to operate the rover take black and white images.The 2020 rover will carry color cameras that
will take higher resolution images.Curiosity carried just one camera to record its descent and landing,
placed on the bottom of the rover to look down.The 2020 rover will carry additional cameras that will look up at the
descent stage that carries the descent rockets, a camera on the descent stage
looking down at the rover, and a final camera on the backshell to image the
parachute opening.

With
these new cameras, being an armchair explorer of Mars will get, as they say, a
whole lot better.

In
one other item of Mars 2020 rover news, the current cost estimates for the
mission appear to be in the $2.14 – $2.35 billion range instead of the previously
quoted $1.5 billion.A reasonable
portion of this increase likely comes from the new figures representing
inflation through launch and operations, while the original cost estimates
were, I’m told, were in 2015 dollars.At
the new figures, the 2020 mission, given inflation, still will be considerably
cheaper than the Curiosity mission on which much of the design will be based.

The
final major news for Mars exploration was NASA’s announcement that it would
like to fly a new orbiter to Mars in the early 2020s (see here).NASA will need a new orbiter to act as a
communications relay for future lander missions (such as a sample return fetch
mission).The agency could fly a fairly
simple orbiter to do just this task.Instead the agency is considering flying a highly capable orbiter that
would use solar electric propulsion (SEP).

NASA
is considering a range of options for an early 2020s orbiter to replace the
Mars Reconnaissance Orbiter (MRO) currently at Mars.At a minimum, the new orbiter would act as a
communications relay for future landed missions.In the most expansive scenario, the new
orbiter would carry a much larger payload than any spacecraft has done in the
past to Mars.Credit: NASA.

All
previous Mars missions have used rockets to enter Mars orbit.Solar electric engines, such as those used by
the Dawn and Hayabusa-2 missions, provide a great deal more cumulative
thrust.By using SEP, the new orbiter
could spiral into Martian orbit.At it
lowers its orbit, it could rendezvous with each of Mars’ tiny moons for
in-depth studies.Then the orbiter could
switch from a near equatorial orbit (where the moons are) to a polar orbit to
allow it to study the entire Martian surface.

NASA’s
Mars program manager stated that the agency would like to have the orbiter
carry a substantial scientific payload (one chart lists a capability to host up
to 300 kg of instruments, which would be a very substantial payload).The agency has not stated a preference for
what types of instruments – a future scientific definition team would make
those recommendations.However, we can
do some informed speculation.

In
the 2000s, two scientific definition teams looked at science that then future
orbiters could make.The highest priority measurements would be to
study the upper atmosphere and trace gases in the atmosphere.Time has moved on, and the MAVEN orbiter is
at Mars studying the upper atmosphere and the 2016 European-Russian orbiter will
study trace gases.

The
panels in the 2000s did recommend that future orbiters carry high resolution
cameras to image possible landing sites and carry out scientific imaging.Since the mid-2000s, the HiRise camera on the
Mars Reconnaissance orbiter has been imaging the planet at 25 to 32 cm pixel
resolution.The HiRise team described a
possible future instrument that would use the same optics, but would provide
color imaging across the entire image.(See
here.) (The current
HiRise camera has color only for the center fifth of each image.)A future camera also could add imaging in
spectral bands in the near infrared that would allow studies of surface
composition at high resolution.This
future camera could also acquire stereo images to allow 3D analysis of each
scene.

Another
concept for a future high resolution camera comes from Malin Space Science
Systems that has built cameras for several Mars missions.(See here.) This camera would
carry a bigger telescope than HiRise camera, and the orbiter would fly closer
to the planet -- skimming just above the top of the atmosphere at perihelion --to acquire images at 5 to 10 cm pixel
resolution.This finer resolution would
allow more detailed scientific studies of surface features, such as the fine
sedimentary bands that are often almost visible in current HiRise images.(The published abstract for this proposal
doesn’t discuss whether the camera would image in multiple color bands.It also doesn’t say how narrow the image
strips would be.HiRise’s lower
resolution likely would provide wider image strips.)

Another
proposal suggested that a future mission might carry a suite of radar
instruments and laser to map the surface and subsurface in detail.(See here.) Ground penetrating
radar instruments are already at Mars mapping the subsurface stratigraphy.However, their capabilities are limited by
the power and mass available to them within the overall suite of instruments
the orbiters carried.The proposal
suggests that a future orbiter carry one radar optimized for subsurface
stratigraphy and a second for surface mapping that would be able to penetrate
the sand and dust that covers much of the planet to image the rock structures
below. The proposal also recommended flying a new generation Laser Ranging and
Detection (LiDAR) instrument that would remap the altimetry of the surface at
much higher resolution.A new orbiter
such as the one NASA is discussing would have the power and payload mass to optimize
instruments such as these along with a high resolution camera.

Another
key capability of the proposed orbiter is that it would use laser optical
communication to return data to Earth as well as newer generation radio systems
(Ka band).The limit on how much data
past and current orbiters have been able to return has not been the
instruments, but instead the bottleneck of the communications system.High resolution cameras and radar instruments
want to be data hogs, and a new generation orbiter with advanced communication
could be an enabling technology to map much larger areas of the planet at high
resolution.

This
orbiter has just been discussed publicly as a concept for the first time in the
last couple of months.None of NASA’s
scientific panels have looked into missions past 2020.They may recommend another mission
instead.It’s also not clear where the
money for the mission would come from.NASA’s planetary program will be funding the development of the $2
billion-ish Europa mission in the early 2020s.If the agency also wants to continue developing a mixture of the smaller
Discovery and New Frontiers missions in the same time frame, a major new Mars
orbiter may stretch the budget.A next
generation Mars orbiter would provide new instrument eyes to study the fourth
planet.We will need to wait and see
whether the programmatic priorities and budgets line up to enable it to fly.

About Me

You can contact me at futureplanets1@gmail.com with any questions or comments.
I have followed planetary exploration since I opened my newspaper in 1976 and saw the first photo from the surface of Mars. The challenges of conceiving and designing planetary missions has always fascinated me. I don't have any formal tie to NASA or planetary exploration (although I use data from NASA's Earth science missions in my professional work as an ecologist).
Corrections and additions always welcome.